MR and magnetisation transfer imaging in cirrhotic and fatty livers

PURPOSE: To determine whether low-field MR fat/water separation and magnetisation transfer (MT) techniques are useful in studying the livers of patients with parenchymal liver diseases in vivo. MATERIAL AND METHODS: MR and MT imaging of the liver in 33 patients (14 with primary biliary cirrhosis, 15 with alcohol-induced liver disease, and 4 with fatty liver) was performed by means of the fat/water separation technique at 0.1 T. The relaxation time T1 and the MT contrast (MTC) parameter of liver and spleen tissue were measured, and the relative proton density fat content N(%) and MTC of the liver were calculated from the separate fat and water images. The value of N(%) was also compared with the percentage of fatty hepatocytes at histology. RESULTS: The relaxation rate R1 of liver measured from the magnitude image, and the difference in the value of MTC measured from the water image compared with the one measured from the fat and water magnitude image, both depended linearly on the value of N(%). The value of N(%) correlated significantly with the percentage of the fatty hepatocytes. In in vivo fatty tissue, fat infiltration increased both the observed relaxation rate R1 and the measured magnetisation ratio (the steady state magnetisation MS divided by the equilibrium magnetisation MO, MS/MO) and consequently decreased the MT efficiency measured in a magnitude MR image. The amount of liver fibrosis did not correlate with the value of MTC measured after fat separation. CONCLUSION: Our results in studying fatty livers with MR imaging and the MT method show that the fat/water separation gives more reliable parametric results. Characterisation of liver cirrhosis by means of the MTC parameter is not reliable, even after fat separation.     

Application of high-performance size-exclusion chromatography to study the autoxidation of unsaturated triacylglycerols

A combination of solid-phase extraction (SPE) and high-performance size-exclusion chromatography (HPSEC) was used to study the autoxidation of triacylglycerol (TAG) mixtures separated from low-erucic acid rapeseed oil and butter oil. The samples were autoxidized in the dark at 40°C for four weeks. The polar compounds of the autoxidated samples were separated by SPE (NH₂ stationary phase), and the polar fraction was further characterized by HPSEC with a series of three size-exclusion columns and an evaporative light-scattering detector. The polar fraction contained TAG polymers, polar TAG monomers (PTAG) and diacylglycerols. Peroxide values and anisidine values of the samples were also measured. By using three different types of TAG mixtures, it could be demonstrated that the PTAG content of the TAGs increases during autoxidation. A slight increase was also detected in polymer content. The correlation between PTAG content and the comparative measurements was considered significant. The results indicate that the measurement of PTAG and polymeric material content by HPSEC analysis can be used when studying the autoxidation level of edible oils and in characterizing the autoxidation products of different molecular sizes.     

Fatty Acid,Phytosterol, and Polyamine Conjugate Profiles of Edible Oils Extracted from Corn Germ,Corn Fiber,and Corn Kernels

This study compared the profiles of fatty acids, phytosterols, and polyamine conjugates in conventional commercial corn oil extracted from corn germ and in two “new-generation” corn oils: hexane-extracted corn fiber oil and ethanol-extracted corn kernel oil. The fatty acid compositions of all three corn oils were very similar and were unaffected by degumming, refining, bleaching, and deodorization. The levels of total phytosterols in crude corn fiber oil were about tenfold higher than those in commercial corn oil, and their levels in crude corn kernel oil were more than twofold higher than in conventional corn oil. When corn kernel oil was subjected to conventional degumming, refining, bleaching, and deodorization, about half of the phytosterols was removed, whereas when corn fiber oil was subjected to a gentle form of degumming, refining, bleaching, and deodorization, only about 10% of the phytosterols was removed. Finally, when the levels of polyamine conjugates (diferuloylputrescine and p-coumaroyl feruloylputrescine) were examined in these corn oils, they were only detected in the ethanol-extracted crude corn kernel oil, confirming earlier reports that they were not extracted by hexane, and providing new information that they could be removed from ethanol-extracted corn kernel oil by conventional degumming, refining, bleaching, and deodorizing.     

Self-reinforcement and hydrolytic degradation of amorphous lactic acid based poly(ester-amide), and of its composite with sol-gel derived fibers

The self-reinforcing and hydrolytic degradation of an amorphous poly(ester-amide) (PEA) based on lactic acid have been studied and compared with those of poly-L-lactide (PLLA). The studied PEA-rods were self-reinforced (SR) by solid-state die drawing resulting double shear strength. The hydrolytic degradation of PEA was studied during exposure to phosphate buffered saline at pH 7.4 and at 37 °C for 18 weeks. The degradation and mechanical properties of PEA were also followed in a self-reinforced composite structure consisting of PEA and sol-gel derived SiO₂-fibers (SGF, 8 wt %). The hydrolytic degradation of the SR-PEA-rods with and without SG-fibers was significantly faster than that of SR-PLLA-rods. The weight average molecular weight (M _w) of PEA decreased by 90% from the initial M _w during the first 6 weeks in hydrolysis, when the M _w of the PLLA decreased by 10%.     

Acetylated Trivalent Mannobioses: Chemical Modification,Structural Elucidation,and Biological Evaluation

People suffering from allergies can be treated with repeated injections of increasing amounts of a specific allergen. This type of specific immunotherapy is currently the only way to treat the underlying pathological immune response associated with an allergy. The approach can afford long‐lasting protection, but the process takes 3–5 years, can produce allergic reactions, and in severe cases treatment is often aborted due to anaphylaxis. However, treatment can be optimized with the use of specific adjuvants that modify the immune response, its duration, and that increase the production of the correct type of antibodies. In the pursuit of such adjuvants, two new trivalent acetylated β‐(1→2)‐linked mannobioses based on a previously discovered lead molecule were prepared. The new molecules, along with the previously developed lead, were investigated by rigorous NMR and molecular modeling experiments in order to elucidate their behavior and preferred conformations in solution. Furthermore, the molecules were subjected to a biological investigation in which their immunostimulatory properties were evaluated by assessing their effect on the production of T_H2‐type cytokine interleukin‐4 (IL‐4) and T_reg pro‐inflammatory cytokine tumor necrosis factor (TNF). Treatment of peripheral mononuclear blood cell cultures from patients suffering from birch allergy with birch allergen Bet v induced a strong IL‐4 response, whereas the same treatment together with the trivalent acetylated mannobioses caused significant suppression of the induced IL‐4.     

Sustainable chemical technology through catalytic multistep reactions

For sustainable production of chemicals, new reactions, methods and manufacturing processes must be designed in a safe, compact, flexible and energy efficient manner. One tool to produce chemicals in a more sustainable way is to use various types of catalytic processes. Currently, a paradigm shift is taking place in chemical synthesis and technology through combining organic synthesis, biocatalytic methods as well as homogeneous and heterogeneous catalysis into efficient one-pot operations and various domino/cascade- and tandem/sequential-type processes. Several examples are presented, highlighting challenges and opportunities of this approach.     

Oxidation reactions of steryl esters in a saturated lipid matrix

In the present study, the formation and further reactions of intact steryl ester hydroperoxides were followed in a tripalmitin matrix maintained at 100 °C. The effects of the acyl moiety and its unsaturation degree, and of the sterol structure were investigated. Intact steryl ester hydroperoxides were isolated from the lipid matrix by a developed solid-phase extraction (SPE) method and were determined by HPLC–ELSD. Further reactions of hydroperoxides were followed by determining secondary oxidation products of sterol by GC-FID/MS and oligomers by HPSEC-RI. The oxidation of sterol decreased when its solubility in the lipid medium was increased by introduction of acyl moiety. Increased unsaturation of the acyl or steryl moiety of steryl ester shortened the induction period and increased the oxidation of both steryl and acyl moieties. Thus, by changing the chemical and physical properties of sterols, their oxidation may be greatly affected.     

A comparison of the effect of medium- vs. long-chain triglycerides on the <Emphasis Type="Italic">in vitro</Emphasis> solubilization of cholesterol and/or phytosterol into mixed micelles

Despite clinical evidence of the cholesterol-lowering effects of phytosterols, the exact mechanisms involved are still unclear. Displacement of cholesterol by phytosterols from mixed micelles, which is due to their greater hydrophobicity, is one of the hypotheses for the lumenal effects contributing to the reduction of intestinal cholesterol absorption. In this study a dynamic in vitro lipolysis method was used to examine the solubilization behavior of cholesterol and/or phytosterols during lipolysis to probe the efficacy of cholesterol displacement from mixed micelles by phytosterols. The effects of lipid chain length on sterol solubilization were studied by using microcrystalline suspensions containing 17% phytosterol or cholesterol, formulated in long-chain TG (LCT) and medium-chain TG (MCT). When digesting cholesterol suspended in LCT, the entire cholesterol dose was incorporated into the micellar phase. For the cholesterol formulation suspended in MCT, 50.3% of the initial dose was recovered in the micelles. Under the respective conditions, we observed lower solubilization of phytosterols than of cholesterol (roughly fourfold). Only 25% of the initial phytosterol dose was solubilized from suspensions formulated with LCT, and 13% was solubilized from MCT formulations. Co-administration of phytosterol and cholesterol suspensions showed a significant reduction of cholesterol solubilization, particularly when dosed in MCT, with ≈25% of the cholesterol dose solubilized. Insignificant amounts of cholesterol were displaced by phytosterols when cholesterol was presolubilized in the mixed micelles. The results show that, compared with LCT, mixed micelles containing MCT lipolysis products have a reduced solubilizing capacity for cholesterol, which adds to the effectiveness of the phytosterols in displacing cholesterol. This suggests potential benefits of using medium chain length lipids in cholesterol-lowering phytosterol products.